A bicycle drivetrain includes all the components that propel the bike forward, such as the crankset, chainrings, chain, cassette (or freewheel), derailleurs, and shifters.

It converts the cyclist’s pedaling effort into movement of the bike.

The drivetrain’s design and the number of gears determine the bike’s speed range and how easy it is to pedal in various terrains.

Modern bicycles might feature drivetrains with a wide range of gears for versatility or a single speed for simplicity.